From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- .../bindings/chrome/google,cros-ec-typec.yaml | 77 ++++++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml (limited to 'Documentation/devicetree/bindings/chrome') diff --git a/Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml b/Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml new file mode 100644 index 000000000..fd1a45987 --- /dev/null +++ b/Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml @@ -0,0 +1,77 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/chrome/google,cros-ec-typec.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Google Chrome OS EC(Embedded Controller) Type C port driver. + +maintainers: + - Benson Leung + - Abhishek Pandit-Subedi + - Andrei Kuchynski + - Łukasz Bartosik + - Jameson Thies + +description: + Chrome OS devices have an Embedded Controller(EC) which has access to + Type C port state. This node is intended to allow the host to read and + control the Type C ports. This binding is compatible with both the + cros-ec-typec and cros-ec-ucsi drivers. The cros-ec-typec driver + supports the host command interface used by the Chrome OS EC with a + built-in Type-C port manager and external Type-C Port Controller + (TCPC). The cros-ec-ucsi driver supports the USB Type-C Connector + System Software (UCSI) interface used by the Chrome OS EC when the + platform has a separate power delivery controller (PDC). The node for + this device should be under a cros-ec node like google,cros-ec-spi. + +properties: + compatible: + enum: + - google,cros-ec-typec + - google,cros-ec-ucsi + + '#address-cells': + const: 1 + + '#size-cells': + const: 0 + +patternProperties: + '^connector@[0-9a-f]+$': + $ref: /schemas/connector/usb-connector.yaml# + required: + - reg + +required: + - compatible + +additionalProperties: false + +examples: + - |+ + spi { + #address-cells = <1>; + #size-cells = <0>; + + cros_ec: ec@0 { + compatible = "google,cros-ec-spi"; + reg = <0>; + interrupts = <35 0>; + + typec { + compatible = "google,cros-ec-typec"; + + #address-cells = <1>; + #size-cells = <0>; + + connector@0 { + compatible = "usb-c-connector"; + reg = <0>; + power-role = "dual"; + data-role = "dual"; + try-power-role = "source"; + }; + }; + }; + }; -- cgit v1.3.1